1. Field of the Invention
This invention relates generally to the field of digital systems design, and more specifically to the design of such systems wherein a small library of modules, with a regular structure amenable to printed circuit board or integrated circuit packaging, are used to directly translate a directed-graph designed system into a hardware configuration.
2. Description of the Prior Art
For many years the design of large digital systems has followed a largely intuitive approach in which the boundaries between hardware and software are usually defined before most of the system itself has been designed. Until recently, the hardware was designed with the primary object of employing the minimum number of components rather than with a view to attaining complete reliability, and, where exhaustive simulation was not possible, problems would often appear after the hardware had been released. Software is usually designed by a team rather than by a single person, a process which often causes interfacing problems. The release of major software elements of a system is frequently followed by a series of corrections which may continue for several years.
For the past several years, researchers have been experimenting with various techniques for the generalized design of digital systems. One approach has been to define systems by directed graphs. These graphs have certain properties which allow the stepwise analysis of entire systems for logical and structural consistency without the necessity for exhaustive simulation. A further advantage of using directed graphs in the design process is that they allow decisions on the hardware/software boundary to be postponed until the designer has sufficient information to make an intelligent choice. More detailed information on this type of representation may be found in Bradshaw, F. T., "Structure and Representation of Digital Computer Systems," Doctorial Thesis, Case Western Reserve University, Cleveland, Ohio, January, 1971; and Rose, C. W., "A System of Representation for General Purpose Digital Computer Systems," Doctorial Thesis, Case Western Reserve University, Cleveland, Ohio, September, 1970.
Once a system is designed using such concepts, it becomes necessary to synthesize hardware realizations from these directed graphs. It is desirable to have a small library of standard modules having a regular structure amenable to standard printed circuit boards or integrated circuit packaging, with which one can directly build the needed hardware from the graphical representation using building-block techniques. It is to this end that the present invention is directed.